[Expression pattern of hsa-miR-9 and its association with BCL6 in EBV-positive and EBV-negative Burkitt lymphoma cell lines].

OBJECTIVE: To investigate the differential expression pattern of hsa-miR-9 between EBV-positive and -negative Burkitt lymphoma cell lines and its association with BCL-6. METHODS: The expression of hsa-miR9 and BCL-6 mRNAs in EBV(+) Raji and EBV-Ramous cells in mRNA levels were detected using fluorescence quantitative PCR (QRT-PCR). The two cells lines were transiently transfected with hsa-mir9-inhibitor and hsa-mir9-minicsvia Oligofectamine 2000, and the changes in BCL6 expressions was detected using QRT-PCR and Western blotting. Annexin V/PI staining was used to analyze the apoptosis and morphological changes of the transfected cells. RESULTS: The expression of Hsa-miR9 and BCL-6 was significantly higher in EBV(+) Raji cells than EBV(-) Ramous cells (P<0.01). BCL-6 mRNA and protein expression was reduced in EBV(+) Raji cells after transfection with hsa-miR9-inhibitor but up-regulated in EBV(-) Ramous cells transfected with hsa-miR9-minics. Flow cytometry revealed a significantly decreased apoptosis rate in EBV(+) Raji cells transfected with hsa-miR9-inhibitor but an increased rate in EBV(-) Ramous cells transfected with hsa-miR9-minics, and the results were confirmed by microscopic observations. CONCLUSION: Hsa-miR9 positively regulate the expression of BCL-6 and apoptosis of EBV(+) Raji cells and EBV(-) Ramous cells.

Re-expression of microRNA-150 induces EBV-positive Burkitt lymphoma differentiation by modulating c-Myb in vitro.

Burkitt lymphoma (BL) is a highly aggressive B-cell lymphoma that includes two forms of BL differing in Epstein-Barr virus (EBV) infection status, EBV-positive and EBV-negative. Although many efforts, such as high-intensity, short-duration combination chemotherapy, have been devoted to improving therapy for this rapidly proliferating neoplasm, there are still significant treatment-associated toxicities. Therefore, there remains a need for novel effective therapeutic strategies. MicroRNAs play a role in "fine tuning" the physiological and pathological differentiation process, by which cells can rapidly regulate dynamic events such as cell-lineage decisions and morphogenesis. This unique miRNA feature shifts the traditional one drug target paradigm to a novel one drug multiple targets paradigm. Here, we found that BL cell lines showed an extremely low expression of microRNA-150 (miR-150), and then restored miR-150 expression at physiologic levels in BL cell lines Daudi, Raji, BJAB, and Ramos. The results showed that re-expression of miR-150 reduced proliferation of Daudi and Raji cells. Furthermore, Daudi and Raji, both of which are of EBV-positive germinal center B-cell origin, transduced with miR-150 can be rescued to differentiate toward B-cell terminal stage. However, no significant changes were observed in BJAB or Ramos cells, which are of EBV-negative germinal center B-cell origin. Of note, re-expression of miR-150 also resulted in decreasing c-Myb protein levels. Additionally, c-Myb knockdown in Daudi and Raji cell lines recapitulated the partial characteristics similar to that caused by re-expression of miR-150. Taken together, our findings show that miR-150 can induce EBV-positive BL differentiation by targeting c-Myb.

Effect of shRNA targeting mouse CD99L2 gene in a murine B cell lymphoma in vitro and in vivo.

Mouse CD99 antigen-like 2 (mCD99L2) has previously been confirmed to be expressed in murine B lymphoma (A20) cells by our group. The present study aimed to establish a mCD99L2­downregulated A20 cell line and to investigate the effect of shRNA targeting mCD99L2 in A20 cells in vitro and in vivo. Four pLenti6/mCD99L2 expression vectors containing the mCD99L2 shRNA-expressing cassette were constructed, transfected into A20 cells and stable mCD99L2-downregulated A20 subclones, termed A20-mCD99L2- cells, were established and identified by quantitative PCR and western blot analysis. Light and transmission electron microscopy, MTT assay, flow cytometry and immunofluorenscence labeling were used to observe the morphological, biological and phenotypic characteristics in vitro. Some of the A20-mCD99L2- cells exhibited H/RS­cell like morphology, a decreased proliferative ability, a prolonged G2 phase and increased CD30 and CD15 expression. Upon injecting cells into nude or immunocompetent BALB/c mice, tumorigenesis, tumor growth, morphology and phenotypes in vivo were observed. A20-mCD99L2- cells induced tumors in nude and BALB/c mice, but with less potency in the latter compared with the controls. Similar morphological, biological and phenotypic characteristics were observed in the A20-mCD99L2- cell-induced tumors as those in vitro. Several cytokines including CD30T, IL-12p40/p70, IL-3, IFN-γ, CXCL16, MIP-1α and CD40 were upregulated following mCD99L2 downregulation when detected using antibody arrays. The results from western blot analysis indicated that the regulation of mCD99L2 expression may involve the activated nuclear factor-κB pathway in the murine B lymphoma cells. The present study provides data for further investigation into the mCD99L2 gene in tumor cells.

Comparison of three methods for the detection of Epstein-Barr virus in Hodgkin's lymphoma in paraffin-embedded tissues.

The percentage rate of Epstein-Barr virus (EBV)-positive cases of Hodgkin's lymphoma (HL) ranges between 20 and 70% in various studies worldwide. To further explore the definite rate in China, three methods, including immunohistochemistry for EBV latent membrane protein 1 (LMP1), in situ hybridization (ISH) for EBV-encoded RNA (EBER)-1 and polymerase chain reaction (PCR) for EBV BamHI­W fragment, were employed to detect EBV in 59 cases of HL in China using paraffin-embedded tissue samples. Our results revealed that the PCR method presented the highest (44/59, 74.6%) detection rate among the three methods. The other two methods identified 66.1% (39/59, LMP1) and 67.8% (40/59, EBER1 ISH) EBV-positive results, respectively. Three samples were positive for LMP1 but negative when using EBER1 ISH, while another four samples were EBER1-positive but LMP1-negative. Of the four major histopathological subtypes of HL, the lymphocyte predominant (LR) subtype is the one most frequently associated with EBV, followed by the mixed cellularity (MC), nodular sclerosis (NS) and lymphocyte depletion (LD) subtypes. Our results also indicated the seldomly reported fact that EBV-positive cases in children were more numerous than those of adults with HL.

CPT-11 Chemotherapy Rescued A Patient with Atypical Sclerosing Epithelioid Fibrosarcoma from Emergent Condition.

Sclerosing epithelioid fibrosarcoma (SEF) is a rare and poorly defined variant of fibrosarcoma, but generally insensitive to chemotherapy and progresses with poor prognosis. We report the marvelous effect of irinotecan hydrochloride (CPT-11) chemotherapy in rescuing a patient with atypical SEF from emergent condition, who underwent recurrences after several treatment methods. Small dose of CPT-11 was administered to the patient, with which, the size of superficial mass (cervical lymph node) gradually decreased observed by the naked eyes in 5 days. X-ray and CT image proved a marked reduction in the size of the tumor. CPT-11 is valuable for the treatment of this aggressive sarcoma. In condition of emergency caused by sarcoma oppression, administering a tolerable small dose of topoisomerase I-inhibiting drug could be a beneficial choice.

CD99 triggers upregulation of miR-9-modulated PRDM1/BLIMP1 in Hodgkin/Reed-Sternberg cells and induces redifferentiation.

CD99 is a 32-kDa transmembrane glycoprotein that is encoded by the MIC2 gene. Our study was carried out to examine the role of CD99 in tumor progression of classical Hodgkin lymphoma (cHL). Here, we showed that lowly expressed CD99 protein in cHL cell lines and primary cHL cases correlates with the deficient expression of the positive regulatory domain 1 (PRDM1/BLIMP1). In addition, cHL cell lines showed high levels of miR-9 expression. We determined that the upregulation of CD99 induced expression of transcription factor PRDM1, a master regulator of plasma-cell differentiation, which is also a target for miR-9-mediated downregulation. Indeed, inhibition of miR-9 also triggered upregulation of PRDM1 expression. Furthermore, overexpression of CD99 resulted in changed growth features and reorganization of actin cytoskeleton. As upregulation of CD99 led to a decrease in cHL diagnosis marker CD30 and CD15 and an increase in plasma-cell differentiation marker CD38 and the restoration of B-cell makers PAX5, CD79α and CD19, we suggest that downregulated CD99 leads to the prevention of plasma-cell differentiation in Hodgkin/Reed-Sternberg (H/RS) cells. Furthermore, these data indicate that CD99 may control miR-9 expression, which directly targets PRDM1. Altogether, these results reveal a CD99-miR-9-PRDM1 molecule axis in lymphomagenesis of cHL and suggest that upregulation of CD99 in H/RS cells induces terminal B-cell differentiation, which may provide a novel therapeutic strategies for cHL.

[Expression of miR-9 in B lymphocytes and B cell lymphomas cell lines and its significance].

OBJECTIVE: To investigate the expression of miR-9 in B lymphocytes, B cell lymphoma and classical Hodgkin's lymphoma (cHL) cell lines and its significance. METHODS: CD19(+) B lymphocytes were sorted from normal lymph node by magnetic beads. Total cellular micro-RNA was extracted from cHL cell line L428, B cell lymphoma cell lines Ly1 and Ly10 (diffuse large B cell lymphoma), Raji cells (Burkitt's lymphoma) and CD19(+) B lymphocytes, respectively. These micro-RNAs were separately transformed into cDNA by reverse transcription. The expression levels of miR-9 were measured by fluorescence quantitative PCR. In situ hybridization was used to detect the expression of miR-9 in cell lines. RESULTS: The expression of miR-9 was high in L428 cells (104.44 ± 1.61), and low in cell lines of B cell lymphoma (Ly1: 2.17 ± 0.38; Ly10: 1 ± 0.015; Raji: 2.65 ± 0.89), and extremely low in CD19(+) B lymphocytes (0.0026 ± 0.00040). Compared with that in the other cell lines, the expression of miR-9 in L428 cells was statistically significant (P < 0.05). miR-9 localized in the cytoplasm diffusely and strongly in L428, but scattered and slightly with some prominent distribution around the nuclear membranes in Ly1 and Ly10, and only weakly in Raji. CONCLUSIONS: miR-9 highly expressed in cHL cell line and might be a molecular marker for diagnosis and treatment of cHL.

Nuclei micro-array FISH, a desirable alternative for MCL diagnosis.

Mantle cell lymphoma (MCL) is a rare, specific lymphoma subtype. Though the morphologic and immunophenotypic features of MCL have been well described in recent literatures, it is still a diagnostic dilemma because of its frequent confusion with other small B cell lymphomas (SBCLs). In the present study, we primarily focus on establishing a sensitive and specific method for the diagnosis of MCL, which is efficient to distinguish this disease from other SBCLs. We carried out our investigation for MCL and other SBCLs (including SLL, FL, MZL, and MALT) on their feature of morphology, immunophenotype, and t(11;14)(q13;q32) translocation analysis based on polymerase chain reaction (PCR) and interphase nuclei micro-array fluorescence in situ hybridization (FISH). The morphologic and immunologic analysis showed the positive rate of cyclin D1 was 76.47% in MCL, which was significantly higher than that in other SBCLs. The positive rate of t(11;14) translocation was 25.81% and 35.48%, respectively, tested by general and semi-nested PCR, while 93.10% positive rate was shown with low background and strong signals pattern when tested by Nuclei micro-array FISH. Our research shows that t(11;14) translocation is a special and useful diagnostic marker for MCL, and detection of the marker by nuclei micro-array FISH is convenient and economic, especially more sensitive and specific than other methods for the diagnosis of MCL.

[Preparation of RNA probe for cd99l2 gene of zebrafish labeled with digoxingenin-UTP].

OBJECTIVE: To study the expression pattern of cd99l2 gene during zebrafish development, the RNA probes for whole-mount in situ hybridization were prepared in this study. METHODS: The cd99l2 fragment obtained by RT-PCR was cloned into pGM-T Easy, then the plasmids were linearized with the restriction enzymes SacII or SalI. Using Sp6 or T(7) RNA polymerase, the digoxingenin-labeled antisense and sense probes were synthesized and confirmed by whole-mount in situ hybridization. RESULTS: The plasmid cd99l2/pGM-T was constructed. cd99l2 gene expression pattern during embryogenesis of zebrafish was examined using the antisense probe, and intense expression was detected in the central nervous system during zebrafish development. CONCLUSION: The antisense probe can be used for study of the spatial and temporal distribution of cd99l2 during zebrafish development using the sense probe as control.

Dieulafoy's lesion with intra-abdominal haemorrhage: a novel association.

Dieulafoy's lesion is an uncommon but important cause of gastrointestinal bleeding, especially with respect to the upper gastrointestinal tract wherein massive, life-threatening haemorrhage occurs from a calibre-persistent submucosal artery. This report describes a case of a 60-year-old man with gastric Dieulafoy's lesion presenting with exogastric haemorrhage, which was diagnosed following a pathological examination.

[Primers for detecting gene rearrangement in different regions of immunoglobulin heavy chain genes and their application in diagnosis of paraffin-embedded lymphoma tissues].

OBJECTIVE: To analyze and optimize the gene rearrangement primers of different frame regions (FR) of immunoglobulin heavy chain (IgH) genes by bioinformatic methods and explore the application of these primers in the detection of paraffin-embedded lymphoma tissues. METHODS: Three pairs of primers from IgH FR1, FR2 and FR3 regions (P1c, P2A and P31, respectively) were selected as the B cell gene rearrangement primers after comparison of the gene fragments in 44 IgH variable and 6 joining regions. Using one pair of T cell receptor (TCR) gamma primer as the T cell gene rearrangement primer, 101 histopathologically confirmed lymphoproliferative samples including 80 B cell lymphomas, 14 T cell lymphomas, and 7 reactive proliferative lymph nodes were examined by PCR for gene arrangement. The DNAs from DG75 and Jurkat cell lines were used as the positive controls for B and T cell lymphoma, respectively, with those from reactive proliferative lymph nodes as the negative control. RESULTS: The positivity rates of IgH primers (P1c, P2A and P31) in the 80 B cell lymphomas were 37.5% (30/80), 52.5% (42/80) and 70.0% (56/80), respectively, and only one of the 14 T cell lymphoma cases was positive for the primers, suggesting significant differences in the detection rates of B cell lymphomas by the 3 primers. The detection rate was increased to 83.9% by combining the results by P31 and P2A primers. No positivity was found in the proliferative reaction tissues. CONCLUSION: Primers from IgH FR3 region genes are more sensitive than that from the FR1 and FR2 regions in the detection of gene rearrangement in paraffin-embedded lymphoma tissues. The detection rates can be increased by combining the results with the primers for IgH FR3 with that of FR2.

[Value of combinational detection by IgH and IgL primers in improving detection rate of lymphoma gene in paraffin-embedded tissue].

BACKGROUND & OBJECTIVE: Clonality detection through amplifying immunoglobulin heavy chain (IgH) by polymerase chain reaction (PCR) is a useful tool in diagnosis of lymphoma, but the false negative rate is high, especially in paraffin-embedded tissues. This study was to explore the value of tumor tissue microdissection and combinational detection of IgH and immunoglobulin light chain (Ig kappa or Ig lambda) in diagnosis of non-Hodgkin's lymphoma (NHL). METHODS: Two pairs of conventional primers for IgH and T-cell receptor gamma (TCRgamma), 2 novel designed pairs of primers for Ig kappa and Ig lambda were used to detect 58 paraffin-embedded blocks, which had been diagnosed by pathology and histochemistry. Of the 58 cases of lymph node tissues, 39 were B-cell lymphoma, 16 were T-cell lymphoma, and 3 were reactive proliferative lymph node tissue. Lymphoma cell lines DG75 and Jurkat were used as control. RESULTS: The positive rates of IgH primers (P1) and IgL primers (P kappa/P lambda) were 79.5% and 71.8% in the 39 cases of B-cell lymphoma (P>0.05), 6.3% and 12.5% in the 16 cases of T-cell lymphoma, respectively. The positive rate was greatly increased to 92.3% in combinationally detecting the primers for IgH and P kappa/P lambda. There was no positive detection among the reactive proliferative lymph node tissues. CONCLUSION: B-cell lymphoma detection rate can be significantly improved by the combination of IgH and IgL gene rearrangement primers, which provides efficient assistant method for the diagnosis and differential diagnosis of lymphoma.

[Detection of bcl-2/IgH gene rearrangement in diffuse large B cell lymphoma by hemi-nested PCR].

OBJECTIVES: To explore a sensitive and specific method for detection of bcl-2/IgH gene rearrangement in diffuse large B cell lymphoma (DLBCL), and verify the credibility of the established method. METHODS: bcl-2/IgH hemi-nested PCR primers were designed using the professional primer design software. Fifty-two samples of pathologically diagnosed DLBCL and 10 fresh tonsil tissues were amplified using hemi-nested touch down-PCR to detect bcl-2/IgH gene rearrangement. The PCR products were cloned and sequenced. RESULTS: bcl-2/IgH gene rearrangement was detected in 6 of 52 DLBCL samples and 2 of 10 fresh tonsil tissues using one-way method. By using the hemi-nested PCR for the second round amplification, 5 of DLBCL were positive, but all of the fresh tonsil tissues were negative. The positive PCR products were sequenced and analyzed on the Internet, 3 of 8 cases obtained by one-way method were false positive, 5 positive cases amplified using hemi-nested PCR were all bcl-2/IgH gene rearrangement. PCR products of 3 false positive cases were homologous to BAC331191 and LLNLR-245D11 in human chromosome 19 and RP11-498P10 in chromosome 1. CONCLUSION: There are false positive results using common primers for detecting bcl-2/IgH gene rearrangement. The mechanism may be that highly homologous sequences to human genome exist in commonly used primers. The specificity of the diagnosis could be improved by hemi-nested PCR using the combination of primers we designed and the traditional ones.

Investigation of T-cell receptor-gamma gene rearrangement in gastrointestinal lymphomas by PCR-SSCP analysis.

AIM: To analyze the characterization of T-cell receptor-gamma (TCR-gamma) gene rearrangement in the gastrointestinal lymphomas and evaluate the value of PCR-SSCP analysis in gastrointestinal lymphomas investigation. METHODS: TCR-gamma gene rearrangement segments of gastrointestinal lymphomas were cloned and sequenced. Single clone plasmid and mixed clone plasmids were subsequently submitted to PCR-SSCP analysis to investigate the relationship between the number of amplified clones and band patterns of the amplified products. The PCR products of TCR-gamma gene rearrangement of 40 gastrointestinal lymphomas were electrophoresed on agarose gels and the positive cases on agarose gels were studied by SSCP analysis. RESULTS: The sequencing showed that TCR-gamma gene rearrangement of the gastrointestinal lymphomas included functional gene and pseudogene with extensive variety in the junctional regions. In SSCP analysis, the number of the single-stranded bands was about two times of the number of amplified clones, and double-stranded band became broad with the increased number of the amplified clones. Thirteen of the 25 B-cell gastrointestinal lymphomas and 14 of the 15 gastrointestinal T-cell lymphomas were positive detected on agarose gel electrophoresis. Of the positive cases detected by SSCP analysis, 3 B-cell lymphomas and 13 T-cell lymphomas showed positive bands. The other cases showed only smears. The rearranged pattern included 13 monoallelic gene rearrangements and 3 biallelic or oligoclonal gene rearrangements. CONCLUSION: The pattern of TCR-gamma gene rearrangement in gastrointestinal lymphomas are similar to that of the nodular lymphomas. PCR-SSCP analysis for TCR-gamma gene rearrangement can be applied both for adjuvant diagnosis of gastrointestinal lymphomas and analysis of the gene rearrangement pattern. The ratio of TCR-gamma gene rearrangements occurred in T-cell gastrointestinal lymphomas is significantly higher than that in B-cell gastrointestinal lymphomas. The gene rearrangement pattern involves monoallelic and biallelic (or oligoclonal) gene rearrangement.

Touch-down PCR and single-strand conformation polymorphism for detecting clonal T cell receptor gamma gene rearrangement in lymphoid leukemia.

OBJECTIVE: To explore the value of detecting clonal T cell receptor gamma (TCR-gamma) gene rearrangement with touch-down PCR and single-strand conformational polymorphism analysis (SSCP) in the diagnosis of lymphoid leukemia. METHODS: The DNA of peripheral blood leucocytes from lymphoid leukemia patients were extracted for amplification of the TCR-gamma gene rearrangement with the consensus primers and touch-down PCR. The PCR products were analyzed by agarose gel electrophoresis, direct DNA sequencing and SSCP analysis. The positive control cell line DNA was mixed in different proportions with the DNA extracted from reactive lymphoid tissue to test the sensitivity of the touch-down PCR. RESULTS: Fifteen of 18 T lymphoid leukemia and 2 of the 4 B lymphoid leukemia patients were identified to be positive by agarose electrophoresis. The positive PCR products were further analyzed by SSCP analysis, which showed discrete bands. Direct DNA sequencing confirmed the clones to be TCR-gamma gene rearrangement, and the sensitivity of touch-down PCR was 1%. CONCLUSION: Consensus primers for studying TCR-gamma gene rearrangement in combination with touch-down PCR can effectively amplify the clonal TCR-gamma gene rearrangement in T lymphoid leukemia.

[Unspecified peripheral T cell lymphoma with distinct lymphoid follicules].

OBJECTIVE: To investigate the morphological features and immunophenotype of unspecified peripheral T cell lymphoma with distinct lymphoid follicular growth pattern. METHODS: Three cases of peripheral T cell lymphoma with special pathohistological features were collected. Morphologic analysis and immunohistochemical staining for CD3, CD45RO, CD43, CD20, CD79a, cyclinD1, bcl-2, CD4, CD8 and S-100 were performed. PCR was used to study TCR gamma gene rearrangements. RESULTS: The main symptoms of all the three patients with the primary sites of cervix and lower jaw. There were intermittent fever and skin rashes in the course of the disease. Morphological study showed lymphoid follicular reactive hyperplasia, mantle zone disappear, prominent infiltration of marginal zones by medium-sized tumor cells with clear cytoplasm and significant nuclear atypia. The immunophenotypic profile confirmed that they were T cell lymphomas. TCR gamma gene rearrangements were found in all the three patients. CONCLUSION: In some unspecified peripheral T cell lymphomas, the distinct follicular growth pattern and incomplete effacement of the lymph node architecture make it necessary to differentiate them from reactive hyperplasia, marginal zone B cell lymphoma, follicular B cell lymphoma and mantle cell lymphoma.

Arsenic trioxide-induced apoptosis of human malignant lymphoma cell lines and its mechanisms.

OBJECTIVE: To investigate the responses of human Burkitt lymphoma cells to arsenic trioxide (As2O3) and the possible mechanisms. METHODS: Epstein-Barr virus (EBV)-positive human B-lymphoma Raji cell line and EBV-negative human B-lymphoma BJAB cell line were used as in vitro models to assess the cell apoptosis by morphology and DNA agarose gel electrophoresis. Protein expression was analyzed using Western blotting. RESULTS: After 24-hour treatment with the 2, 5 and 10 micromol/L As2O3, the concentrations of As2O3 achievable in vivo, cell apoptosis was induced in human Burkitt lymphoma BJAB cells at the rates of 47.6%+/-4.8% (Mean+/-SD, n=3), 66.4%+/-5.1%, 87.0%+/-7.3% and at 35.5%+/-3.8%, 51.5%+/-6.2%, 62.2%+/-7.9% respectively in Raji cells, corresponding to the concentration of As2O3. EBV-infected Raji cell line was less sensitive to As2O3 than EBV-negative BJAB cell line (P<0.05). As2O3-induced apoptosis was accompanied by down-regulation of Bcl-xL protein expression and activation of apoptosis protein caspase-3, as identified by Western blotting. CONCLUSION: As2O3 exerts apoptosis-inducing effects on human Burkitt lymphoma cells through down-regulation of Bcl-xL protein expression and activation of apoptosis protein caspase-3, and may serve as a candidate therapeutic agent against malignant lymphoma for both systemic and local therapies.

Expressions of latent membrane protein 1, p53 and bcl-2 proteins and their significance in Hodgkin's lymphoma.

OBJECTIVE: To study the expressions of latent membrane protein 1 (LMP1), p53 and bcl-2 proteins and investigate their significance in the pathogenesis of Hodgkin's lymphoma. METHODS: Immunohistochemical staining was used to examine the expressions of LMP1, bcl-2, and p53 proteins in 31 paraffin-embedded tissue samples from Hodgkin's lymphoma. RESULT: The positivity rates of LMP1, p53 and bcl-2 proteins were 58.1% (18/31), 61.3% (19/31) and 35.5% (11/31), respectively, showing a statistically significant difference between the expressions of the former 2 proteins. CONCLUSION: p53 may be involved as an important agent in the pathogenesis of Hodgkin's lymphoma induced by LMP1, whereas bcl-2 appears unrelated to the development of this disease.